Woodhouse on flash storage

Peter Robinson pbrobinson at gmail.com
Mon Oct 5 11:56:11 EDT 2009


On Mon, Oct 5, 2009 at 4:44 PM, Martin Langhoff
<martin.langhoff at gmail.com> wrote:
> On Mon, Oct 5, 2009 at 5:27 PM, Chris Ball <cjb at laptop.org> wrote:
>> I don't think there's much we can use Dave's advice for given the
>> choice of microSD.  If a microSD card that had a passthrough mode
>> to access the raw flash existed, his argument would be that we
>> should consider using that mode.
>
> Exactly. To expand: we are in the same pickle as the rest of the
> industry. This article gives some good background reading to David's
> words http://lwn.net/Articles/353411/ -- and if you've been following
> her writing, Valerie knows a ton about FSs, including work on ZFS.

Ted Ts'o, who's one of the lead dev's on ext4, has had some very
interesting articles about the various issues with SSDs, erase blocks
and all of the previously mentioned issues. I believe also SD cards
handle things slightly differently than sata ssds too.

His main blog is here http://thunk.org/tytso/blog/
But some of the interesting ones are:
http://thunk.org/tytso/blog/2009/02/20/aligning-filesystems-to-an-ssds-erase-block-size/
http://thunk.org/tytso/blog/2009/02/22/should-filesystems-be-optimized-for-ssds/
http://thunk.org/tytso/blog/2009/03/01/ssds-journaling-and-noatimerelatime/

>From memory the plan is to use ext4 so he might well have some of the
best options for optimal options for SD. I know from my own experience
the cheeper SD cards tend to have a lot more issues.

Peter



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